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循环期间从列表列表中移除元素

python-2.7 python

-1

fugu · 技术社区 · 7 年前

我有一个数据结构 info (一份清单?)我正在构造如下:

pages     = [12, 41, 50, 111, 1021, 121]
bookCodes = ['M', 'P', 'A', 'C', 'A', 'M']
sentences = ['THISISASENTENCE',
             'ANDHEREISONEMOREEXAMP',
             'ALLFROMDIFFERENTBOOKS',
             'ANDFROMDIFFERENTPAGES',
             'MOSLTYTHESAMELENGTHS',
             'THISISSHORT'
             ]
info = list(zip(bookCodes, pages, sentences))

然后我一次一封信地迭代这个列表(压缩列表)。因为有些句子比其他句子短(例如。 THISISSHORT )我比其他句子先到达最后一个元素在这种情况下,我希望完全屏蔽这个元素,使其不受未来迭代的影响 但我不想在开始循环之前过滤它 是的。

import random

letters_read = 0

for i in range(21):
    random.shuffle(info)
    for b, p, s in info:
        if len(s) <= i+1:
            print("End of sentence reached at position %s. Sentence: %s" % (i, s))
            continue    
        letters_read += 1

我正在使用 continue 跳过这种情况下的元素,并打印一条消息以指示已到达其结尾的句子。但是,这将继续遍历此元素,直到循环结束。 我想从进一步的迭代中排除这些元素。

我有~ 10,000 我列表中的句子,它们可以大到 2000 字符,所以我假设通过屏蔽这些句子,而不是跳过,将提高我的脚本的效率。

在迭代过程中是否可以从这个数据结构中删除/屏蔽一个元素?我试过用 info.remove(i) 和 del info[i] ,但这不起作用(因为这不是一个列表)。

输出以下内容:

End of sentence reached at position 10. Sentence: THISISSHORT
End of sentence reached at position 11. Sentence: THISISSHORT
End of sentence reached at position 12. Sentence: THISISSHORT
End of sentence reached at position 13. Sentence: THISISSHORT
End of sentence reached at position 14. Sentence: THISISASENTENCE
End of sentence reached at position 14. Sentence: THISISSHORT
End of sentence reached at position 15. Sentence: THISISSHORT
End of sentence reached at position 15. Sentence: THISISASENTENCE
End of sentence reached at position 16. Sentence: THISISASENTENCE
End of sentence reached at position 16. Sentence: THISISSHORT
End of sentence reached at position 17. Sentence: THISISASENTENCE
End of sentence reached at position 17. Sentence: THISISSHORT
End of sentence reached at position 18. Sentence: THISISASENTENCE
End of sentence reached at position 18. Sentence: THISISSHORT
End of sentence reached at position 19. Sentence: THISISASENTENCE
End of sentence reached at position 19. Sentence: MOSLTYTHESAMELENGTHS

期望输出 :

End of sentence reached at position 10. Sentence: THISISSHORT
End of sentence reached at position 14. Sentence: THISISASENTENCE
End of sentence reached at position 19. Sentence: MOSLTYTHESAMELENGTHS

4 回复 | 直到 7 年前

MA1 7 年前

您需要复制原始列表,然后遍历新副本并从原始列表中移除项

for item in list(original_list):
  ...
  original_list.remove(item)

在您的情况下,代码如下所示

total_read = 0

for i in range(21):
    random.shuffle(info)
    for index, value in enumerate(list(info)):
        b, p, s = value
        if len(s) <= i+1:
            print("Overshot! Shouldn't see this sentence anymore: %s" % (s))
            info.pop(index)
        print s[:i+1], i, s

        total_read += len(s[i + 1])

ankit agrahari 7 年前

您可以使用del从压缩列表中删除项目

for i in range(21):
    q=0
    for p, b, s in info:
        if len(s)<=i+1:
            print(f'Overshot! Remove this element {s} {q}')
            del info[q]
        print(f"{s[:i+1]}, {i}, {s}")
        total_read += len(s[i+1])
        q+=1

Sreyas 7 年前

复制列表并遍历副本并从原始目录中删除该项。

for i in info[:]:
  info.remove(i)

Ma0 7 年前

先清理输入,然后循环:

sentences = ['THISISASENTENCE',
             'ANDHEREISONEMOREEXAMP',
             'ALLFROMDIFFERENTBOOKS',
             'ANDFROMDIFFERENTPAGES',
             'MOSLTYTHESAMELENGTHS',
             'THISISSHORT'
             ]
max_len = len(max(sentences, key=len))  # kudos ZachGates
print max_len  # 21
sentences = filter(lambda x: len(x)==max_len, sentences)
print sentences  # ['ANDHEREISONEMOREEXAMP', 'ALLFROMDIFFERENTBOOKS', 'ANDFROMDIFFERENTPAGES']

现在你可以像以前那样继续了。